1. Field of Invention
This invention relates to a chemical process, and product which uses the process, for reducing tar and nicotine in cigarettes.
2. Description of the Related Art
The existence of tar and nicotine in cigarette smoke has presented a very serious problem in cigarettes for many years. The extent of the health hazards associated with the tar and nicotine have been the focus of many studies and much publicity in recent years. The tar and nicotine in the cigarette smoke is the result of partial combustion. The tar and nicotine exists in both the mainstream smoke, which the smoker draws from the cigarette, and the sidestream smoke, which is commonly known as "second-hand" smoke. Thus, there has been a long-felt need for effective reduction and control of tar and nicotine levels in smoking articles, such as cigarettes, pipes, and cigars.
Conventionally, attempts to reduce or control tar and nicotine levels in cigarette smoke have focused on filters which physically remove particulate matter, such as tar and nicotine, from the mainstream smoke condensate, thereby reducing the total particulate matter ("TPM") in the smoke condensate. Thus, the range of cigarettes, from the "full flavor" cigarette to the "light" cigarette to the "ultralight" cigarette, are graded according to the effectiveness of their filters, which can eliminate approximately 50% of the potential tar and nicotine in a normal unfiltered cigarette. Further refinement of filter technology has led to the invention of laser perforated high porosity air dilution filters to further reduce the tar and nicotine in the mainstream smoke. Even these filters, however, fail to reduce the tar and nicotine levels sufficiently and fail to provide adequate control of the tar and nicotine levels.
To-date, the prevailing features of tar and nicotine control in the cigarette industry are all through "physical methods." Physical methods are limited in their range of control and cannot totally eliminate all tar and nicotine from the cigarette. Additionally, the physical methods change flavor and character of the smoke, thereby reducing the enjoyment of smoking and leaving the smoker unfulfilled. For example, some of the light and ultra-light cigarettes have very fine filters which require a great deal of effort to "draw" smoke from the cigarette. While the filter reduces tar and nicotine in the mainstream smoke, it does not reduce the tar and nicotine in the sidestream smoke which does not exit through the filter. Thus, the problem of "Second-Hand Smoke" is not alleviated.
The latest technology is a "heat" cigarette, known as Eclipse and sold by R. J. Reynolds, which employs a carbon core in the cigarette. This new cigarette attempts to reduce the tar and nicotine levels by reducing the combustion in the cigarette. This new cigarette does not burn at the conventional 800.degree. C., but instead heats the tobacco to less than 300.degree. C. This low temperature reduces combustion, thereby reducing tar formation and also the distillation of nicotine. The "no burn" cigarette purportedly produces lower levels of tar and nicotine in the mainstream and sidestream smoke than previously known cigarettes. Even the new cigarette Eclipse, however, accomplishes the reduction of tar and nicotine by a physical property: temperature. The new Eclipse, or "no burn" cigarette, reduces the tar and nicotine by more than 70%, but, as with conventional filters, it changes the flavor and character of the smoke, thereby reducing the pleasure of smoking. Cigarette burning produces flavor. The "no burn" cigarette likely tastes different and its acceptability in the market-place is uncertain.
Several earlier patents have attempted chemical methods of reducing tar and nicotine in cigarettes. Chemical approaches in facilitating the reduction of harmful organics and /or carbon monoxide in smoking compositions are referenced in numerous patents. These fall into three general categories: salts of carboxylic acids, metals, and oxides of transition metals.
In U.S. Pat. No. 4,489,739, Mattina, Jr. and Selke used citrate salts of potassium, ammonium and magnesium as an additive in smoking preparation. When the input is between 6.5% to 20% based on weight of the filler, the reduction of carbon monoxide is 25 to 50%. Other carboxylates such as acetate and tartrate were also effective in reducing carbon monoxide. In tobacco, citrates are found in combination with nicotine and other alkaloids. The salts of the alkaloids are not as volatile as the free base and therefore their incorporation may reduce some of the harmful organics in the smoke condensate. The nitrates are also a component of the tobacco in-vivo.
U.S. Pat. No. 3,180,458 correlates the reduction of tar to the increase in tobacco burn rate. In U.S. Pat. No. 3,380,458 by Touey et al., other salts of potassium and sodium nitrates were introduced as tobacco additives. They reported that a salt additive of 6-9% caused tar reduction by as much as 34%. The inventors believed that the nitric acid salt possesses a much higher thermal decomposition temperature than the burning tobacco. Their presence at the burning tobacco of the cigarette reduces tar formation. The salts of carboxylates and the like were also incorporated into cigarette wrappers to reduce either tar or carbon monoxide from the side stream smoke in U.S. Pat. No. 5,121,759, U.S. Pat. No. 4,561,454, U.S. Pat. No. 4,231,377 and U.S. Pat. No. 3,782,393. All of these prior art patents evidence the long-felt need for effective reduction and control of tar and nicotine levels in cigarettes.
Chemical additives of metals with valence +2 for the purpose of removing nicotine from tobacco smoke are discussed in U.S. Pat. No. 5,462,072 to Brown and Robertson. They demonstrated that the ferrous ammonium sulphate and not the ferric ammonium sulphate is effective in removing about 17% of the nicotine from the tobacco smoke. British Pat. No. 841,074 disclosed that tobacco treated with the platinum group metals lowers the benzopyrene carcinogen in the smoke. U.S. Pat. No. 4,236,533 to de Clara discloses that the treatment of a tobacco composition with an mixture of catalysts composed of gold, silver, platinum and cerium compounds reduces a small percentage of polycyclic aromatic hydrocarbons and nicotine. U.S. Pat No. 4,317,460 to Dale and Rooney describes the catalysts of tin and other materials for low temperature oxidation of carbon monoxide to carbon dioxide used in smoking product filters.
U.S. Pat. No 4,397,321 to Stuetz discloses a tobacco smoking preparation comprising tobacco, a potassium or calcium compound, and a transition metal compound. The potassium and calcium compounds in the form of oxides, hydroxides, nitrates, carbonates, permanganates, carboxylic acid salts promote oxidation. The preferred transition metal compounds in the Steuetz patent are oxides of iron and manganese. This patent discloses three examples, none of which specifically use a potassium or calcium compound. Instead it uses a nondescript cigarette ash from previous runs, which is backblended into a new tobacco substance. Metal analysis of the ash showed that calcium comprised 20% and potassium only amounted to 12% by weight. The treatment reduced the level of carbon monoxide in the smoke. The input of transition metal oxides are tremendously large, from 40 mg to 400 mg of manganese. The single example given for reduction of tar was 55% while the reduction of nicotine was 64%.
U.S. Pat. No. 3,943,940 Minami proposed a smoking filter to remove nicotine from the smoke. An aqueous solution of potassium permanganate (KMNO.sub.4) and chlorine is impregnated in the filter. The author also discusses that the aqueous KMNO.sub.4 solution is unstable and they use chlorine to stabilize it. There was no example presented to document a claim of formation of nicotinic acid (see FIG. 1). The Minami patent erroneously labeled nicotinic acid as an oxide of nicotine. It is not even clear to what extent permanganate really contributes to the oxidation of nicotine if the water barrier filter is also removing nicotine from the smoke.
Metal Oxides of Zinc are especially effective in causing a decrease of polycyclic aromatic hydrocarbon by about 50% (See Norman et al. 1973 U.S. Pat. No. 3,720,214). The same group of authors also discloses in U.S. Pat. No. 3,893,464, U.S. Pat No. 4,216,784, and U.S. Pat. No 4,248,251, that zinc oxide, palladium, nitric oxide in combination with each other are also effective in lowering the polycyclic aromatic hydrocarbon.
All of these prior art chemical methods have failed to be commercially successful primarily because the results attained are less significant than those achieved by the physical means as described above. Many of the prior art conventional methods can accomplish a reduction of tar and nicotine only by 40% or less. Some methods border on alchemy such as employing cigarette ash. Some use precious metals of gold, platinum or silver or add inordinate amounts of chemicals such as 400 mg of manganese dioxide. Some additives are impractical, such as a liquid filter containing potassium permanganate and chlorine. Finally, most prior art chemical methods appear to have an all or none effect, i.e., there is no dose-response relationship. The only exception to the cited references is the patent to Touey. The response in Touey, however, is low and levels off at less than 35% tar reduction.
Oxidation appears to be the common element in the chemical approaches to reducing tar, nicotine, polycyclic aromatic hydrocarbon and carbon monixide. Most of the known oxidants are the metal oxides, which achieve less tar and nicotine reduction than the physical methods.
Permanganate is an active oxidant which is at a higher oxidation state than its oxide, manganese dioxide. Therefore, it is unstable especially in the presence of moisture and other oxidizable organic material. Scheme 1, shown below, depicts the reaction whereby permanganate consumes 2 molecules of water and converts to the more stable and less reactive oxidant manganese dioxide. There is also a dramatic color change because permanganate ion is red to purple in color and the manganese dioxide is brown. This is readily observed when permanganate powder is placed on a piece of white paper. In a matter of a few days the paper turns brown. When powdered permanganate is blended with tobacco, which like paper is also cellulosic, and upon storage, the permanganate is progressively deactivated and is converted to manganase dioxide. Hence, any prior claim of permanganate as the active oxidant in tobacco resulted in disadvantages. The additive of permanganate, unless it is protected from direct contact with tobacco and moisture, is converted to manganese dioxide.
In the present invention, permanganate is emulsified in Sterotex and is devoid of contact with tobacco and moisture. It is therefore safely protected from premature oxidation by the inert Sterotex.
In the high temperature coal of the burning cigarette, carbonized tobacco oxidizes organics to carbon dioxide and water. Consequently, this zone becomes highly deficient in oxygen, thereby inhibiting complete combustion. The organics present in this zone are volatile intermediates of pyrolysis. Nicotine remains unchanged in this zone and is inhaled along with other organic condensates such as polycyclic aromatic hydrocarbons in the mainstream smoke. At or near the char line of a burning cigarette, the thin tobacco paper permits the infusion of large amounts of oxygen and thus enhances the combustion of nicotine to be found in the sidestream gaseous phase.
Oxidation is both natural and common in the burning cigarette. The present invention uses an oxidant emulsified in an inert combustible vegetable oil Sterotex. The oxidant, Permanganate, donates two molecules of oxygen to overcome the oxygen deficiency at the burning coal, and the Sterotex enhances the burning of the tobacco to promote the complete oxidation of organics. Clearly tar and nicotine and other harmful organics are lowered in the mainstream smoke condensate.